This study aimed to assess the usability of CalmSoul, a digital cognitive behavioural therapy (DCBT) platform designed for adolescents with a social anxiety disorder (SAD). Forty-five adolescents between the ages of 14 and 18 diagnosed with SAD participated in the intervention study, with 15 of them completing usability testing sessions. The intervention included two types of content - generic and specific. Each consisted of ten modules for adolescents and nine separate parental modules. Participants were randomly assigned to three groups: specific, generic, and waiting list. The Social Anxiety Scale for Adolescents (SASA) was conducted in four stages: pre-test, mid-test, post-test, and three-month follow-up. The results indicated no significant differences between the two experimental groups regarding the outcome variable at ten weeks or during a 3-month follow-up. The findings are preliminary and should be interpreted with caution due to potential limitations in power. The future research should strive for larger sample sizes to strengthen the reliability of the results. Participants were particularly positive about CalmSoul’s usability, highlighting its ease of use. They also provided valuable suggestions for improvement, such as enhancing navigation and providing clearer therapy module instructions. The average System Usability Scale (SUS) score was 79.8, indicating favourable perceptions of usability. The treatment completion rate was notably high at 94.4%, highlighting participant engagement. Future research should focus on refining content for improved efficacy. In conclusion, CalmSoul demonstrates potential as a user-friendly CBT platform for adolescents with SAD, warranting further investigation.